Derivative Instruments - Summary of Gains (Losses) Recognized in Earnings for Fair Value Hedges, Other Economic Hedges and Customer-Related Positions (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Asset and Liability Management Positions [Member] | Other noninterest income [Member] | Other Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	$ 1		$ (42)
Asset and Liability Management Positions [Member] | Interest Rate Contracts [Member] | Other noninterest income [Member] | Fair Value Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(19)		(13)	(7)
Asset and Liability Management Positions [Member] | Interest Rate Contracts [Member] | Mortgage banking revenue [Member] | Other Economic Hedges [Member] | Futures and Forwards [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	6	33	(69)	569
Asset and Liability Management Positions [Member] | Interest Rate Contracts [Member] | Mortgage banking revenue [Member] | Other Economic Hedges [Member] | Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	64	54	210	200
Asset and Liability Management Positions [Member] | Interest Rate Contracts [Member] | Mortgage banking revenue [Member] | Other Economic Hedges [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	17	(5)	238	(264)
Asset and Liability Management Positions [Member] | Foreign Exchange Forward Contracts [Member] | Commercial products revenue [Member] | Other Economic Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(24)	(16)	(41)	18
Asset and Liability Management Positions [Member] | Equity Contracts [Member] | Compensation expense [Member] | Other Economic Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings			1	1
Asset and Liability Management Positions [Member] | Credit Contracts [Member] | Other noninterest income/expense [Member] | Other Economic Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings		2		1
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Other noninterest income [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(20)	13	329	(288)
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Other noninterest income [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	28	(10)	(307)	298
Customer-Related Positions [Member] | Foreign Exchange Rate Contracts [Member] | Commercial products revenue [Member] | Forwards, Spots and Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	$ 13	$ 15	$ 45	$ 36